VT340 Emulation

Grant Taylor cctalk at gtaylor.tnetconsulting.net
Sat Jun 26 12:37:15 CDT 2021

On 6/26/21 6:43 AM, Peter Corlett via cctalk wrote:
> A bit of both. The USB communications device class (CDC) is designed 
> for modems, and it can be hit-and-miss trying to speak to something 
> else.

<I can't tell GIF>
Are you commenting about USB-to-Serial (a.k.a. FTDI) devices or USB 
devices in general?

I commonly referred to USB as Useless <REDACTED> Bus between the late 
'90s and mid '00s.  Supporting it, especially on non-bleeding edge 
computers / OSs, was ... not pleasant.

> Of course, that doesn't prevent one from ignoring that standard and 
> just creating a bespoke USB device which happens to produce RS232, 
> and FTDI do just that. FTDI's devices are better than standard CDC, 
> but that's not a terribly high bar.


> Well, these things will contain a UART of some form, because how 
> else could they work?

Snark warning:  Have you seen a WinModem?

Seriously, I could see something blindly sampling the electrical signal 
and then doing everything in software.  As in Digital Signal Processing. 
  No actual knowledge / design as if it's serial until you get the data 
stream out the other end.  Obviously needing comparable to be able to 

> For all I know they may even incorporate an actual 16550 IP core in 
> the design and talk to that from its firmware, although a UART uses 
> bugger all gates by modern standards and you can just get an intern 
> to design one in a lunchbreak rather than pay for an IP core.

I suspect you'd get what you paid for.  IMHO there are too many 
permutations on what constitutes serial.  If anything, this discussion 
supports that.  Even if we limit our scope to be RS-232, RS-422, and 
RS-485 without going further afield.  How much of the serial ecosystem 
do we eliminate if equipment assumes 8-bit?  }:-)

> It doesn't seem impossible to build a decent USB-serial dongle which 
> caters to all of the weird and wonderful edge cases, but the market 
> for such things is small enough that they would be quite expensive 
> to produce, reducing the market further.

I don't know.  Maybe.  I've seen some really fancy things designed by 
people as part of the Retro Computing / Retro Networking hobby.  Perhaps 
someone will take up the torch and a Good (TM) USB to Serial converter, 
open source the design* and someone else will sell PCBs and / or kits 
for it.  Maybe even someone will assemble some and sell them for those 
that don't own a soldering iron or aren't good at using one.

> Something I'm putting off is installing a USB micro-B plug on my 
> old iPod whose 30 pin socket has finally given up the ghost. I could 
> just buy a new one, except they don't make them any more: the current 
> device called an "iPod" is a glorified advertising hoarding which has 
> a usability disaster of a media player bolted on as an afterthought.

Interesting.  I've not heard of anyone doing this.  But I'm not 
surprised that it's possible.

Grant. . . .
unix || die

More information about the cctalk mailing list